The Portaflex is a line of

amplifier An amplifier, electronic amplifier or (informally) amp is an electronic device that can increase the magnitude of a signal (a time-varying voltage or current). It may increase the power significantly, or its main effect may be to boost the v ...

s for electric guitars and bass guitars created by

Ampeg Ampeg is a manufacturer best known for its bass amplifiers. Originally established in 1946 in Linden, New Jersey by Everett Hull and Stanley Michaels as "Michael-Hull Electronic Labs," today Ampeg is part of the Yamaha Guitar Group. Although ...

and originally designed by

Jess Oliver Jess Oliver (born Oliver Jespersen) (January 20, 1926 - June 30, 2011) was a musician, an inventor, electrician and Amplifier repairman best known as the Vice-President of Ampeg and Patent holders, patent holder for many of Ampeg's most successful ...

. Portaflex referred to the amps’ ''porta''ble re''flex'' baffle system. The innovative ‘flip-top’ amplifier head design helped dissipate heat and reduce chassis and tube vibration during use, and inverted to store inside the cabinet for portability. The speaker cabinets were carefully tuned with ports and baffling. The introduction of the Portaflex series established a new standard for bass amplification and completely replaced Ampeg’s previous amplifier lineup. The Portaflex line has many different configurations.

B-15

The first amp in Ampeg’s Portaflex series was the B-15, a 2-channel

tube amplifier A valve amplifier or tube amplifier is a type of electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by sol ...

with per-channel volume controls and shared Baxandall-type

tone control Tone control is a type of equalization used to make specific pitches or "frequencies" in an audio signal softer or louder. It allows a listener to adjust the tone of the sound produced by an audio system to their liking, for example to compensat ...

, housed within a ’flip-top’ tuned-port cabinet design mounted to a dolly. Shortly after the B-15’s introduction in 1960, it became the most popular bass amp in the world. Thanks to the Manhattan Bass Club, there were B-15s in every professional recording studio in New York, and the B-15 was embraced by the most prolific session bass players of the time, such as

James Jamerson James Lee Jamerson (January 29, 1936 – August 2, 1983) was an American bass player. He was the uncredited bassist on most of the Motown Records hits in the 1960s and early 1970s (Motown did not list session musician credits on their releases u ...

and

Bob Babbitt __NOTOC__ Robert Andrew Kreinar (November 26, 1937 – July 16, 2012), known as Bob Babbitt, was a Hungarian-American bassist, most famous for his work as a member of Motown Records' studio band, the Funk Brothers, from 1966 to 1972, as well a ...

Motown Motown Records is an American record label owned by the Universal Music Group. It was founded by Berry Gordy Jr. as Tamla Records on June 7, 1958, and incorporated as Motown Record Corporation on April 14, 1960. Its name, a portmanteau of ''moto ...

in Detroit, Donald “Duck” Dunn at

Stax Records Stax Records is an American record company, originally based in Memphis, Tennessee. Founded in 1957 as Satellite Records, the label changed its name to Stax Records in 1961. It also shared its operations with sister label Volt Records. Stax was ...

in Memphis, and

Chuck Rainey Charles Walter Rainey III (born June 17, 1940) is an American bass guitarist who has performed and recorded with many well-known acts, including Aretha Franklin, Steely Dan, and Quincy Jones. Rainey is credited for playing bass on more than 1,00 ...

in New York and Los Angeles. In subsequent decades, popularity of the B-15 endured, used by bassists like

Darryl Jones Darryl Jones (born December 11, 1961) is an American bass guitarist. He has been recording and touring with the Rolling Stones since 1993. He has also played in bands with Miles Davis and Sting, among others. Career Darryl Jones was born on ...

Justin Meldal-Johnsen Justin Meldal-Johnsen (born March 26, 1970) is an American musician, record producer, songwriter and musical director. He is best known for his work with artists such as Beck, Paramore, Nine Inch Nails, M83, Air, and St. Vincent. Meldal-J ...

, and Owen Biddle.

SB-12

Ampeg manufactured the Portaflex SB-12 model amplifier from 1965-1971. This lightweight (67 pound) cabinet incorporated the flip-top design of other larger Portaflex amplifiers of the time. Although the SB-12 isn't as well known as the more powerful B-15, it is still highly sought after by musicians who use it mainly for studio recording. The 'SB' in SB-12 stood for string bass; the '12' indicates the diameter of the speaker in inches. It contained a single-channel, 25-watt tube amplifier and a single Jensen speaker. Unlike most of the Portaflex line of bass amplifiers, the SB-12 was designed as a universal amplifier. It incorporated two separate inputs, one labeled "Bass" and the other "Instruments".

Gallery

FILE:Ampeg Portaflex B-15N (1967-1968).jpg, Portaflex B-15N (1960s) FILE:Ampeg B15 Bass Amp.jpg, BT-15 (1966/1967-?)

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...

amp head FILE:Ampeg Portaflex B-15N (front).jpg, Portaflex B-15N (1970s) FILE:Ampeg Portaflex PF 350.JPG, Portaflex PF-350 class-D amp head "''RMS power output: 350W @ 4 ohms / Preamp: Solid-state / Power amp: Class D''"

Notes

References

* * * * ;media * {{cite web , ref={{sfnref, Stiles , author = Clint Stiles (stiles72) , title = Ampeg BT-15C , url = http://s554.photobucket.com/user/stiles72/library/Ampeg%20BT-15C?sort=6&page=1 , format = photo gallery , work = photobucket.com

B-15

SB-12

Gallery

Notes

References

Further reading